I think that the reason of this is that for INSERTs, you need not to use the clsql:query, but clsql:execute-command. They differ in that clsql:query expects that the SQL query will return some results, and clsql:execute-command does not expect results. CL-SQL uses libmysql and probably libmysql crashes when you try to extract result from query that does not produces one.But the backtrace and the memory fault are certainly a bad thing here, CLSQL should be more polite to the user